The class of polymers of carbon monoxide and olefin(s) has been known for a number of years. Brubaker, U.S. Pat. No. 2,495,286, produced such polymers in the presence of free radical initiators, e.g., peroxy compounds. U.K. 1,081,304 produced similar polymers of higher carbon monoxide content in the presence of alkylphosphine complexes of palladium salts as catalyst. Nozaki extended the process through the use of arylphosphine complexes of palladium moieties and certain inert solvents. See, for example, U.S. Pat. No. 3,694,412.
More recently, the class of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon, for example copolymers of carbon monoxide and ethylene or terpolymers of carbon monoxide, ethylene and propylene, have become of greater interest, in part because of the greater availability of the polymers. These polymers have been shown to be of the general formula ##STR1## wherein A is the moiety of ethylenically unsaturated hydrocarbon polymerized through the ethylenic unsaturation. For example, when the ethylenically unsaturated hydrocarbon is ethylene the polymer is represented by the repeating formula ##STR2## If propylene is also present in the reaction mixture, the polymer will additionally have units of ##STR3## found randomly throughout the polymer chain. The general process for the preparation of the polymers is illustrated by a number of published European Patent applications including 121,965 and 181,014. This process generally involves a catalyst composition formed from a compound of the Group VIII metals palladium, cobalt or nickel, the anion of a non-hydrohalogenic acid having a pKa below 2 and a bidentate ligand of phosphorous, arsenic or antimony.
The resulting polymers are relatively high molecular weight thermoplastics having utility in the production by methods conventional for thermoplastics of shaped articles such as containers for food and drink or parts for the automotive industry. The polymers have relatively high melting points, generally over 175.degree. C., frequently over 210.degree. C., depending upon the molecular weight and chemical nature of the polymer.
The polymers are further characterized by a high degree of linearity and alternating structure. There is, however, a certain degree of irregularities or defects in the regular pattern of alternating carbonyl and alkylene groups. These defects are thought to be responsible for a lowering of crystallinity of the polymers accompanied by, on occasion, weight loss of the polymer upon heating to the temperatures near or above the melting point of the polymer which are normally associated with methods for processing of thermoplastic polymers, e.g., injection molding or extrusion. It would be of advantage to provide linear alternating polymers of carbon monoxide and at least one ethylenic hydrocarbon which have relatively few irregularities in the polymer chain and are therefore of enhanced crystallinity.